This section provides background information related to the present disclosure which is not necessarily prior art.
A significant challenge with using conventional optical heterodyne or homodyne mixing to detect an arbitrary spontaneous emission is in generating a local oscillator that is coherent with the signal to be detected. Due to the random nature of spontaneous emission, it is impossible to create a local oscillator that is temporally coherent, and thus can constructively mix, allowing heterodyne/homodyne detection, with an arbitrary, spontaneously emitted signal. Since coherence time is inversely proportional to the bandwidth of the detected signal, typical coherence times for broadband emission are extremely short (<picosecond time scales), implying that coherent mixing may only be achieved with picosecond time scale detection, which is not possible with currently available electronic detection technology.